The invention relates to tissue dissectors and tissue retractors for use in the field of surgery. More particularly, the invention relates to a combined dissector-retractor and methods of dissection-retraction to create an anatomic space by using combined or independent dissector-retractor apparatus.
Current methods used for retracting tissue and improving visualization and working space include mechanical separation using metal retractors during surgery, balloon retractors, and direct pressure of an unconfined flow of fluid such as water or CO2 during surgery. A number of retractors have been disclosed and, in the interest of brevity, will not be further described here. The reader is referred to Bonutti, U.S. Pat. No. 5,197,971, Bonutti, U.S. Pat. No. 5,295,994, Bonutti, U.S. Pat. No. 5,345,927, and Moll et al., U.S. Pat. No. 5,309,896, these and all other references cited in this document are expressly incorporated by reference as if fully set forth herein in their entirety. Tissue dissection has also been discussed and, for general considerations, the reader is referred to Bonutti, U.S. Pat. No. 5,163,949, Kieturakis, International Publication No. WO95/32663, Kieturakis et al., EP 0,573,273 A2, published Dec. 8, 1993, Kieturakis et al., International Publications No. WO96/00531, published Jan. 11, 1996, and Fogarty et al., International Publication No. WO96/00597, published Jan. 11, 1996.
Tissue retractors have been particularly useful in orthopedic surgery. There are several orthopedic procedures that have the potential to offer both low cost and patient benefit. Among these is spinal fusion. There are about 200,000 such procedures performed annually in the United States. In general, the procedure is performed to eliminate a ruptured vertebral disk which is causing significant patient discomfort, and subsequently to promote fusion between the then-exposed and adjacent vertebra. This fusion can be promoted by any of several proprietary prosthetic systems or by traditional bone prostheses, or by a combination of the two. Most traditional systems have utilized a posterior approach to the spine.
Several newer systems, some currently under investigation have utilized an anterior approach, and seem to promise better clinical results. The open anterior approach is highly invasive, however, and has led researchers to try a transperitoneal laparoscopic variation to the open procedure. This is an improvement, but still subjects the patient to those same risks associated with invasion of the peritoneum outlined above, but if anything, more severely.
There have recently been several cadaver studies where an extraperitoneal laparoscopic approach to the lumbar spine has been attempted with success. This is a natural target procedure since the dissected space required is essentially the same as that required for aortic reconstruction. Most interesting is that the space dissection requirements are largely the same for all of the prosthetic systems under study.
We have discovered that tissue dissection in combination with retraction can be an important component of the surgical and, particularly, the vascular and orthopedic armamentarium. In many procedures, it would be convenient to provide retraction in the space created by tissue dissection during the course of the subsequent procedure. In balloon dissection, the dissection is performed by a flexible bladder which is inflated in order to create a predetermined space. Once inflated, the bladder generally occupies the extremities of that space. By providing on the surface of this main bladder, a subsidiary bladder or bladders, a secondary inflatable structure can be created which can be activated and serve as a retractor. This secondary bladder can be inflated before or after the primary dissecting balloon is deflated or partially deflated. If necessary, the primary bladder may be evacuated in order to keep it out of the way in the operating space or, once the secondary structure is positioned, the primary bladder integrity may be sacrificed. The secondary structure can be completely contained on or within the surface of the primary dissection bladder, or it may extend beyond the limits of the primary bladder.
One specific instance where this sort of device would be particularly useful is in retroperitoneal access to the lumbar spine, vena cava, and/or aorta and related structures. Balloon dissection in this area can be used to free the peritoneum from the floor of the abdomen, extending up toward or beyond the kidneys, and crossing the midline of the abdomen. The entry incision is advantageously lateral and just above the iliac crest, but may be elsewhere. In the process of this dissection, the peritoneum and contents are lifted superiorly such that they are out of the way of the desired access to the lumbar/aortic space, be it from the anterior midline or from a more lateral approach. The main balloon then fills the space created and, on deflation, the peritoneum and contents return to their normal position. Trendelenburg or other patient positioning can have some beneficial effect, but generally not enough to maintain the desired access. Retraction is desirable. This retraction can be provided by a secondary structure on the primary balloon surface that is inflated and left inflated during the procedure. After the procedure has been completed, the entirety of the bladder may be removed.
In another embodiment, an inflatable structure can be provided which, in concert with the adjacent tissue, provides or tends to provide a space into which surgical instruments can be introduced for purposes of visualization or therapy. In this embodiment, the operating space is between the balloon and the tissue. Depending on tissue behavior and balloon shape, the space may be open, as by xe2x80x9ctenting,xe2x80x9d or may require that the resilience of the balloon-tissue interface accommodate insertion of the instruments. One procedure where this sort of embodiment would be useful is in treatment of carpal tunnel syndrome where space is very limited, but some tenting will occur given adjacent dilation by means of the balloon dissector-retractor.
In another embodiment, the dissector-retractor of the invention is used to gain access to the aorta for repair of an aortic aneurysm. Vascular grafts have been used endoluminally to repair the interior lumen of the aorta as a therapy for aortic aneurysm. However, in certain cases, the aorta will further expand to form a still larger aneurysm and effectively bypass the vascular graft. Therefore, in another embodiment of the present invention, a dissector-retractor is used to create space in which a xe2x80x9cbandingxe2x80x9d procedure, whereby an external repair is effected around the aorta. Sch a repair would provide a radial force in an inward direction.